1. Field of the Invention
The present invention relates to a communication station apparatus and its method of use in a multipoint intercommunication system for performing a multipoint intercommunication by connecting a plurality of points via communication lines.
2. Related Background Art
In recent years, AV (Audio Visual) services utilizing a digital network such as an ISDN (Integrated Services Digital Network) have received a lot of attention since communication services using the ISDN have been put into practical applications, and various kinds of multimedia communication apparatuses such as visual telephone apparatuses, video meeting systems, and the like are increasingly popular.
Normally by connecting a plurality of multimedia communication station apparatuses to a communication station apparatus called an MCU (Multipoint intercommunication Control Unit), multipoint multimedia communications can be realized. Recently, as disclosed in Japanese Laid-Open Patent Applications Nos. 04-326239, 05-22321, and 05-22322, a system for realizing a multipoint intercommunication without using an MCU by connecting a plurality of multimedia communication apparatuses in a chain or loop pattern has been proposed.
In the conventional multipoint intercommunication system, communication paths must be set for the respective multimedia communication apparatuses. As a method of setting communication paths for a multipoint intercommunication, for example, the names of members who plan to participate in a multipoint intercommunication, the telephone numbers of their multimedia communication apparatuses, and the like are registered in groups, and communication paths are set for the registered multimedia communication apparatuses.
However, since the above-mentioned conventional multipoint intercommunication system does not take account of whether or not these registered members actually plan to participate in the multipoint intercommunication, it is often inconvenient to confirm members who actually plan to participate in the multipoint intercommunication or to select members to serve as communication partners from among those who actually plan to participate in the communications.
Upon execution of the multipoint intercommunication, since a communication path is set even for the multimedia communication apparatus of a member who cannot participate in the multipoint intercommunication for some reason, if a public line is utilized for setting the communication path, extra line cost is incurred.
Furthermore, upon execution of the multipoint intercommunication, when available communication lines are divided by the number of points like in a system wherein images at the respective points are synthesized and displayed, the line rate assigned to a member who does not participate in the multipoint intercommunication is wasted, and communication lines cannot be effectively utilized.